last ...

Constants/XCategoryServiceConstants.cs

@@ -0,0 +1,7 @@
+namespace xCategoryService.Constants
+{
+    public struct XCategoryServiceConstants
+    {
+        public const string SubCategoryReference = "SubCat";
+    }
+}

DI/XDIHelperExtension.cs

@@ -8,7 +8,6 @@ using xCategoryService.Interfaces.Entities;
 using xCategoryService.Providers;
 using xCategoryService.Providers.Dtos;
 using xCategoryService.Providers.Entities;
-using xCategoryService.Providers.GraphQL;
 using xCommons.Extensions;
 using xCommons.Helpers;
 using xDataService.Constants;
@@ -284,6 +283,12 @@ namespace xCategoryService.DI
                 new ServiceDescriptor(typeof(IXCategoryDescriptionResourceProvider), typeof(XCategoryDescriptionResourceProvider), lifeTime)
             );
 
+            //
+            // Reference Providers ...
+            services.Add(
+                new ServiceDescriptor(typeof(IXCategorySubCategoryReferenceProvider), typeof(XCategorySubCategoryReferenceProvider), lifeTime)
+            );
+
             //
             // Provider ...
             services.Add(

Interfaces/IXCategorySubCategoryReferenceProvider.cs

@@ -0,0 +1,8 @@
+namespace xCategoryService.Interfaces
+{
+    /// <summary>
+    /// a Service for SubCategory Referencing on Category ...
+    /// </summary>
+    public interface IXCategorySubCategoryReferenceProvider : IXBaseCategoryProvider<int>
+    { }
+}

Providers/XCategorySubCategoryReferenceProvider.cs

@@ -0,0 +1,17 @@
+using xCategoryService.Constants;
+using xCategoryService.Interfaces;
+using xCategoryService.Interfaces.Dtos;
+
+namespace xCategoryService.Providers
+{
+    public class XCategorySubCategoryReferenceProvider : XBaseCategoryProvider<int>, IXCategorySubCategoryReferenceProvider
+    {
+        public XCategorySubCategoryReferenceProvider(
+            IXCategoryServiceProvider categoryProvider
+        ) : base(
+            categoryProvider: categoryProvider,
+            providedFor: XCategoryServiceConstants.SubCategoryReference
+        )
+        { }
+    }
+}